Modern motor vehicles often include one or more driver information and driver assistance systems (hereinafter referred to as in-vehicle information systems) that provide a wide variety of information and entertainment options to occupants in the vehicle. Common services that are provided by the in-vehicle information systems include, but are not limited to, vehicle state and diagnostic information, mapping and navigation applications, hands-free telephony, radio and music playback, and traffic condition alerts. In-vehicle information systems often include multiple input and output devices. For example, traditional buttons and control knobs that are used to operate radios and audio systems are commonly used in vehicle information systems. More recent forms of vehicle input include touchscreen input devices that combine input and display into a single screen, as well as voice-activated functions where the in-vehicle information system responds to voice commands. Examples of output systems include mechanical instrument gauges, output display panels, such as liquid crystal display (LCD) panels, and audio output devices that produce synthesized speech.
Three-dimensional (3D) graphics methods have been widely used in different driver assistance and driver information applications. One typical example is navigation systems based on 3D maps. Photorealistic 3D maps employ photorealistic rendering techniques to visualize the real world scenes in a photorealistic way so that the driver could attempt to match the synthetic appearances of rendered 3D objects in the map with those of real-world 3D objects he could observe through the wind shield. This method could help with fast decision making (e.g., turn-by-turn navigations) for the driver in different driving scenarios. Compared with traditional two-dimensional (2D) maps, photorealistic 3D maps are considered to be more helpful for easy driver orientation and fast location recognition. For example, photorealistic 3D mapping and navigation services are provided by multiple online and offline services including services offered by Apple, Google, and Nokia.
However, there are several drawbacks to using photorealistic 3D graphics in mapping and navigation applications. First, many photorealistic details are too distracting for a user during operation of a vehicle. Second, existing photorealistic solutions only provide limited assistance for the vehicle operator to identify an orientation of the vehicle or identify the location of the vehicle because the photorealistic graphics represent a snapshot of the physical environment around the vehicle that does not necessarily depict the environmental conditions around the vehicle while the vehicle is in operation. In other words, current solutions ignore an important fact that the appearances of real-world objects change noticeably due to, for example, changes in lighting and weather conditions.
Another type of 3D maps is referred to as a stylized 3D map, which is based on non-photorealistic rendering techniques. The stylized 3D map employs an automatic simulation of artistic painting processes to emphasize important visual aspects such as general building shape and appearance, or de-emphasize less important details such as wall textures and window details. In other words, map importance could be highlighted in a stylized way. In addition, the stylized 3D maps enable personalized 3D map view solutions by presenting the 3D world using different artistic styles based on the preference of the vehicle operator.
Compared with photorealistic solutions, the stylized 3D maps present the real-world scene to a driver as an illustration that emphasizes certain elements rather than a photograph that has to introduce every detail that might not be necessary for navigation. On one hand, stylized presentations have reduced the visual distraction problem existing “photorealistic” approaches are facing. On the other hand, even with stylized presentation, the general appearance of the rendered 3D world scene does not always correspond to the physical environment. Consequently, improvements to 3D visualization techniques for in-vehicle information systems that provide dynamic and intuitive displays of maps including dynamic environmental and lighting conditions would be beneficial.